The invention relates to a turbocompressor or motor-compressor, and particularly to an integrated motor compressor unit.
With reference to FIG. 1, integrated motor-compressor units comprise a sealed common casing 10 in which there is an electric motor 12 and a compressor unit 14, for example a multi-stage compressor unit, which comprises a set of bladed wheels like the bladed wheel 16 fitted on a shaft 18. The motor 12 drives a rotor 20 in rotation, this rotor 20 being coupled to the shaft 18 of the compressor 14 through a rigid coupling 22. Bearings 24, 26 and 28 are used to support the shaft line of the motor compressor unit. The assembly is placed in a common casing 29.
During operation, the gas to be manipulated is present at the inlet E of the turbocompressor and is then transmitted to the successive compression stages of the compressor unit to be delivered at the outlet S. An axial bearing block 30 is used to prevent axial displacement of the compressor 14 during operation.
This type or arrangement has the advantage that it considerably simplifies the shaft line of the compressor unit to the extent that the assembly consisting of the motor, its rotor and end bearing blocks, and the rigid coupling and the axial thrust bearing, are located inside the casing and are subjected to the gas pressure at the inlet to the first compression stage. Furthermore, with this type of arrangement, it is possible to provide the shaft line with several compression stages while limiting its length.
However, this type of structure has a major disadvantage to the extent that when it is assembled, the rotor and the shaft driven by the compressor have to be perfectly aligned. Furthermore, fixing the rotor and the compressor shaft considerably degrades the vibrational behaviour of the shaft line.